Background: Capsule endoscopy is a valuable diagnostic method for unexplained gastrointestinal bleeding (OGIB). 183 consecutive patients with OGIB were examined by capsule endoscopy from May 2007 to June 2012 and divided into two groups: group A was those with clear bleeding lesions on capsule endoscopy and group B was those without clear bleeding lesions. In group A, the patients with clear bleeding lesions were examined by capsule endoscopy, and in group B, the patients without clear bleeding lesions were compared and analyzed according to age, sex, history, lesion degree, lesion manifestation, emptying time, intestinal cleanliness, detection rate and diagnosis rate. The detection rate of gastrointestinal bleeding was 84.15%; the detection rate of mucosal lesions in the stomach was 44.16% (68/154); the detection rate of mucosal lesions in the small intestine was 74.02% (114/154); the detection rate of lesions in the colon was 3.89% (6/154); and no lesions were found in the mucosa of the gastrointestinal tract in 29 patients. There were 34 patients with 2 or more lesions. The lesions included small arterial hemorrhages, mucosal erosions, superficial ulcers, polyps, occupancies, ulcers, and diverticula. There was no significant difference between the age and gender of patients in both groups. Group A had more active bleeding, longer medical history, more comorbidities, longer small bowel transit time, better intestinal cleanliness, heavier lesions, and higher lesion detection rate. Conclusion: Capsule endoscopy is an effective and safe screening tool for OGIB, and early capsule endoscopy can improve the prognosis of patients by providing early diagnosis and timely treatment. Attention to patient selection, good bowel cleanliness, improved lesion identification, image interpretation, and comprehensive clinical judgment and follow-up can improve the diagnostic rate of capsule endoscopy and enable timely and clear management of unexplained gastrointestinal bleeding lesions.